1. Field of the Invention
The present invention relates to a protection device for a vehicle-mounted air conditioner compressor, and more specifically to a protection device by which compressor trouble such as lubrication failure or deposition of the refrigerant liquid within the compressor cylinder is avoided by periodic driving of the compressor.
The lubrication system of an air conditioner compressor is constructed so that the lubricant oil of the compressor flows through a heat cycle of the air conditioner along with the refrigerant during the operation of the compressor. Therefore, it is necessary to actuate the air conditioner compressor periodically during the period in which the air conditioner system is rarely used.
2. Description of the Prior Art
In the case of an air conditioner compressor, the lubricant oil of the compressor is atomised and circulates during the heat cycle along with the flow of the refrigerant during the normal operation of the compressor. Therefore, if the compressor is stopped for an excessively long time, during the winter season for example, lubrication failure may occur. Such a lubrication failure will render the compressor difficult to start, or it will cause compressor damage such as wear and tear on the compressor cylinder wall or damage of the compressor seals. For example, if the seals in the compressor are damaged, the refrigerant gas begins to leak. Also, the seals become dry because the lubricant oil is not periodically pressurized and forced between the rubber seal and metal compressor shaft.
Furthermore, if the air conditioner system is not operated for a long time, the refrigerant existing within the heat cycle will be deposited in liquid form, little by little within the compressor cylinder. If the compressor is driven under such a condition, it is under an excessive load by compressing the refrigerant liquid, which will result in compressor damage or slippage of the compressor clutch.
In order to avoid such unfavorable conditions, it is therefore necessary to actuate the compressor periodically for supplying the seals in the compressor with the lubricant and for avoiding the deposition of the refrigerant liquid during a period in which the air conditioner system is not operated.
However, in the case of the prior art compressor protection device, the circuit is designed merely to detect the reduction of refrigerant pressure within the heat cycle by the use of a low pressure switch, and to stop the compressor when the refrigerant amount is not sufficient. Since it does not include means for periodically actuating the compressor, the prior art protecting device is not capable of preventing the compressor from lubrication failure or deposition of the refrigerant within the compressor cylinder caused by a long period of nonuse. Therefore, a periodic manual operation of the air conditioner switch is necessary in the case of the prior art protection device. However such operation of the air conditioner switch is quite troublesome, especially during the winter season when the air conditioner system is not used, although it is necessary for the protection of the compressor and for lengthening the life thereof.
The present invention, based on the recognition of the above mentioned problem, is to provide a compressor protection device for preventing lubrication failure and deposition of the refrigerant by periodic actuation of the compressor.